Glue Choices for Tight or Loose Joinery

Epoxy does best with a looser joint, while other adhesives perform better with tighter joinery. August 29, 2011

QuestionI'm back to making my own cabinet doors and loving it. However, this is the first time I've used beech. Because of how hard and brittle it is, and prone to tear out when running the stick profile, I cut the stick profile in two passes. First pass a climb cut removing 90% of the material and the final cut a standard, removing the rest. At the time I thought it was a great idea, but the joints have just enough slop in them that I'm not comfortable with using my standard Titebond 1 glue. I need something that will span that gap when needed. As I'm a stickler for tight joints, I haven't run into this before and am wondering if a good epoxy would fit the bill here? I can pick up a good Loctite heavy duty epoxy locally or order in (but it won't be here until the end of the week) t-88 gap filling epoxy. Any advice?

Forum Responses(Adhesive Forum)
From contributor J:Epoxy has a tendency of accentuating a wood-to-wood joint with a dark line, so be aware if you go this route. Unstained beech is pretty light, so it might jump out at you. I'd make a few sample doors, one with yellow glue and one with epoxy and stress-test the joints. The problem with epoxy is that in order to be really gap-filling, it needs a filler such as wood flour or colloidal silica, and these fillers turn your liquid joinery ugly, or at least unexpected, in a cabinet door.

From Professor Gene Wengert, forum technical advisor:Keep in mind that epoxy requires a thicker glue line, so that if you would have a tight joint originally and then apply pressure, you might have too thin of an epoxy glue line for the strong joint.

I would encourage you to consider using a jointer on the joints just before glue application to get the perfect gluing surfaces, and then use TB I.

From contributor B:If you are having trouble cutting beech, you need different cutters (new or sharper ones) or a heavier shaper with a power feeder. I stick my beech parts in one pass and do not climb cut. Cuts like a dream. I use a shim kit with my cutters to get the exact fit I want.
From contributor A:TiteBond 3 gap fills almost as well as epoxy.
From contributor I:I agree with contributor A. Although I am a big fan of West System epoxies, I recently read an in depth comparison of glues done by Fine Woodworking Magazine. I was quite surprised to find the Titebond 3 outperformed all other glues in every category, including filling small voids. The only exception to this was maple, where epoxy was stronger. I have switched over to Titebond 3 exclusively, except when I need extended open time, when I will use epoxy with a slow hardener, or Titebond Extend.
From Professor Gene Wengert, forum technical advisor:Many adhesives will fill a gap, but only a few will remain strong. TB III will not remain as strong as epoxy when used in a joint that is not tight... that is, a joint with substantial gaps.

On the other hand, epoxy used in a tight joint will not develop as much strength as TB III (or TB II or TB). The same is true for a loose joint that has high pressure.

In a test such as run by a FW magazine author, one must be very careful, as the test may favor one adhesive over another (for example, epoxy on a tight joint or high pressure joint will favor other adhesives). A thread a few months ago mentioned some of the shortcomings of the tests used in this particular article.

Unless the joint is extremely loose (dry fit), then it would probably be best to use TB rather than epoxy. In many cases, there will be enough strength imparted by the regions where the joint distance is perfect, so that the few spots of gaps and low strength will not affect the overall performance and the overall strength (most joints exceed the strength of the wood and also are stronger than the load applied when they are made properly).

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